The guest request synchronous API from SEV-SNP VMs to the host's security
processor consumes a global resource. For this reason, AMD's docs
recommend that the host implements a throttling mechanism. In order for
the guest to know it's been throttled and should try its request again,
we need some good-faith communication from the host that the request
has been throttled.

These patches work with the existing /dev/sev-guest ABI to detect a
throttling code.

Changes from v1:
  * Changed throttle error code to 2

Cc: Tom Lendacky <Thomas.Lendacky@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Peter Gonda <pgonda@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>

Signed-off-by: Dionna Glaze <dionnaglaze@google.com>

Dionna Glaze (2):
  x86/sev: Rename snp_guest_issue_request's fw_err
  virt/coco/sev-guest: interpret VMM errors from guest request

 arch/x86/include/asm/sev.h              |  4 +--
 arch/x86/kernel/sev.c                   |  6 ++---
 drivers/virt/coco/sev-guest/sev-guest.c | 34 +++++++++++++++++--------
 include/uapi/linux/sev-guest.h          | 16 ++++++++++--
 4 files changed, 42 insertions(+), 18 deletions(-)

-- 
2.38.0.413.g74048e4d9e-goog